Control system



May 9, 1939. F. B. FILLO 2,157,329

CONTROL SYSTEM Filed Feb. 12, 1937 Inventor 1 70x0215 3-H ZZo PatentedMay 9, 1939 UNITED STATES PATENT OFFICE ooN'raoL SYSTEM ware ApplicationFebruary 12, 1937, Serial No. 125,419

18 Claims.

This invention relates in general to controllers and is moreparticularly concerned with the control of power consuming devices suchas employed, for instance, in air conditioning systems.

In the art of air conditioning it is common to cause cooling anddehumidification of air by passing it through a spray of chilled water.The chilling of this water is in many cases accomplished by means of acompression refrigeration system. Due to the fact that the cooling loadof an air conditioningsystem varies considerably with changes in weatherconditions and occupancy, it is desirable to employ a type ofrefrigeration system therefor which has sufiicient flexibility ofoperation to remain reasonably efficient for all loads. For this purposesuch refrigeration systems are provided with a number of compressors,and these compressors are sequentially placed in operation as therefrigeration load increases and are sequentially placed out ofoperation as the load decreases. Automatic control devices have alsobeen employed for effecting this sequential control of the compressors.Heretofore, however, such control devices have been subject to theserious disadvantages of having no provision for sequentially startingthe compressors in the event of a power failure. Thus should therefrigeration load be heavy and all of the compressors be placedinoperation by the sequential controller when a power failure shouldoccur, upon restoration of the power all of the compressors wouldsimultaneously start, this causing an extremely large current to bethrown on the line, and resulting in opening of the circuit breakers.

One object of my invention is, therefore, to provide an air conditioningcontrol system of the type which automatically increases the number ofcompressors placed in operation upon an increase in load, such systemacting upon a failure of power to cause the compressors to be restartedsequentially.

A further object of my invention is the provision of an automaticcontroller of the proportioning type with a means for causing suchcontroller to move to an extreme position upon the occurrence of apredetermined abnormal condition, such movement to extreme positionconditioning the controller to return to a position determined by itscontrol device.

Another object of my invention is the provision of a sequentialcontroller for a plurality of control devices, such controller acting tosequentially actuate said control device in ac- 55 cordance with thecontrolled condition and acting also to actuate said devices in apredetermined manner upon the occurrence of a predetermined secondcondition.

A still further object of my invention is to provide a control means fora plurality of power consuming devices, such means acting upon a powerfailure to disconnect said devices from theirsource of power and tosequentially place said devices into operation upon a resumption.

For a full disclosure of my invention reference is made to the followingdetailed description taken in connection with the accompanying drawing,the single figure of which diagrammatically represents one form which myinvention may take.

Referring to the drawing, the reference char-' acter- I indicates an airconditioning chamber, this chamber being provided with an inlet orreturn duct 2 and a discharge duct 3, this duct being connected to theinlet of a fan 4, the discharge 5 of which communicates with the spaceto be conditioned 6. The fan 4 is provided with a suitable electricmotor I, this motor being connected by the wires 8 and 9 to the lineswitch In which in turn is connected to suitable line wires II and I2. I

Located in the conditioning chamber I is a spray pipe l3 which isprovided with a plurality of jets through which water is forced toprovidev a spray through which the air is passed. Located. beneath thespray pipe I3 is a suitable trough- H which collects the water issuingfrom said spray pipe. Connected to the trough I4 is a drain pipe 15,this drain pipe leading into a cooler I6 which forms the evaporator of acom pression refrigeration system. Connected to the cooler I6 is anoutle pipe l1, this pipe leading to the suction side of a centrifugalpump l8 the discharge of which is connected by a pipe 19 to the spraypipe I 3. The pump I8 is driven by an electric motor 20, this electricmotor being connected by a suitable electrical conduit 20a with thestarting box 2|. From the foregoing it should be seen that when themotor 20 is placed into operation by the starting box 2| refrigeratedwater will be drawn from the cooler l6 and discharged into the pipe |'9,thus passing to the spray pipe l3 wherein it is sprayed over the airpassing through the conditioning chamber, such water then beingcollected -by the trough l4 and passed through the pipe I5 back to thecooler I6.

As mentioned previously, the water cooler I6 forms the evaporator of acompression refrigeration system. This system comprises compressors 22,23 and 24, these compressors being driven respectively by electricmotors 25, 26 and 21. The

. rator l6. The outlet of the evaporator I6 is conand 41 to the suctionsides of the compressors 22,

nected by pipe 43 to a suction header 44, this header being connected bybranch pipes 45,46

23 and 24 respectively.

The compression refrigeration system just described is filled with asuitable refrigerant and operates in the usual manner. The compressorswhen in operation act to raise the pressure of the refrigerant and todischarge this refrigerant at high pressure and in a gaseous state intothe condenser 39 wherein heat is removed from such refrigerant causingit to assume the' liquid state. This liquefied refrigerant is thenpassed through the pipe 40 to the expansion valve 4| wherein itspressure is greatly reduced. Due to this reduction in pressure,evaporation of the refrigerant from the liquid to the gaseous statetakes place, this causing an absorption of heat from the water flowingthrough said evaporator. This gasified refrigerant is then withdrawnfrom the evaporator or cooler |6 by the action of the compressors andagain raised in pressure, this cycle being repeated continuously. Itwill be apparent that with one compressor in operation a certain amountof refrigeration will take place and that' them for controlling theswitches 59, 60, 6|, 62

and 63. Each of these switches 59 to 63 comprise a cam follower blade 64which blade carries a contact adapted for engagement with a similarcontact carried by a stationary contact blade 65. These switches are sodesigned that when the cam follower blade thereof engages the recessedportion of its associatedcam, the contacts will be separated. ,When,however, the associated cam is rotated so that the raised portionthereof engages the cam follower blade such blade will be moved upwardlycausing its contact to be brought into engagement with that carried bythe stationary blade. The cams- 53, 54, 55 and 56 are arranged so as tocause sequential closing of the switches 60 to 63 as the shaft 5| isrotated in a counter-clockwise direction. Thus it will be seen that theshoulder 66 of the cam 53 which separates the raised portion of said camfrom the recessed portion thereof is angularly displaced in acounter-clockwise direction from the corre- I sponding shoulder 61 ofthe cam 54. Similarly the shoulder 61 of cam 54 is displacedcounterclockwise of the shoulder 68 of the cam 55, and

this shoulder is angularly displaced from the shoulder 69 of the cam 56.By this arrangement, when the shaft 5| is rotated in a clockwisedirection sufflcien'tly to cause the recessed portion of the cam 53 toengage the switch 60, said switch will open, and at this time therecessed portions of the cams 54, 55 and 56 will be engaging theircorresponding switches and therefore the switches 60, 6|,62 and 63willall be open. Now as the shaft 5| is rotated in a counter-clockwisedirection the raised portion of the cam 53 will first engage the switch60 causing closing of this switch. Upon further rotation of shaft 5| inthe same direction the raised portion of cam 54 will engage switch 6|causing this switch to close. Similarly, 'upon further rotation of theshaft 5| the switches 62 and 63 will be closed sequentially. Uponrotation of shaft 5| in the opposite direction the opposite action willtake place, this is, the switches 60 to 63 will be opened in reverseorder.

The cam 52 is arranged on the shaft 5| differently from the other cams.This cam is arranged so that the recessed portion thereof engages thefollower portion of the switch 59 so long as the shaft 5| is in anangular position, which causes closing by the cam 53 of the switch 60.Therefore, as the shaft 5| is rotated in a clockwise direction theswitches 60, 6|, 62 and 63 will be opened in reverse order and finallyupon further clockwise rotation, the raised portion of the cam 52 willengage the switch 59 causing closing of said switch. The switch 59therefore remains open so long as any of the switches 60 to 63 remainclosed, and upon opening of the switches 60, 6|, 62 and 63 the switch 59will be closed.

In order to drive the shaft 5| the motor rotors 19 and II are provided,these being mounted upon a shaft to which is secured a pinion 12 whichforms part of a speed reducing gear train 13 the last gear of which ismounted upon the shaft 5|. Cooperating with the rotor 19 is a field coil14, a similar field coil 15 cooperating with the rotor I The rotor 10and its field coil 14 form a motor for driving the shaft 5| in onedirection while the rotor II and its field coil 15 cooperate to form amotor for driving said shaft in the opposite direction. Therefore. whenthe rotor 14 is energized the shaft 5| will be driven in one directionand when. the field coil 15 isenergized said shaft will be driven in theopposite direction.

Mounted also upon the proportioning motor shaft 5| is a cam 16, this cambeing adapted to cooperate with the limit switch 11. This limit switchis formed of a movable contact blade I9 "and a stationary contact blade19, the blade 16 being spring pressed against the blade 19 to cause thecontacts carried by said blades to be normally closed. When the shaft 5|is rotated to its extreme counter-clockwise limit of rotation the raisedportion of thecam 16 will engage the movable blade 18 thereby causing itto be moved away from the stationary blade 19 to disengage the contacts.It should therefore be seen that when the motor shaft 5| is rotated toits extreme counter-clockwise limit of rotation the limit switch 11 willbe opened; Also cooperating with the cam 16 is a limit switch 80, thisswitch being formed in the same manner as the switch 11 and 5| isrotatedto its extreme clockwise limit of rotation.

The reference character 8| indicates a balancing potentiometer, thisinstrument comprising a balancing arm 82 which is mounted upon the shaft5| and which is arranged to cooperate with a balancing resistance 83.

' as the proportioning motor shaft 5| is rotated the balancing arm82-will be shifted across the balancing resistance 83. The purpose ofthis balancing potentiometer will appear as this description proceeds.

Reference character 85 indicates a relay for controlling theenergization of the motor field coils 14 and 15. This relay comprises aU- shaped armature pivoted at 86 and having legs 81 and 88 whichcooperate with relay coils 89 and By this arrangement said actuating armagainst the bellows I06. Upon an increase in temperature within thespace 6 the volatile fluid within the bellows I06 90 respectively.Attached to the armature-by means of an insulating connection is aswitch arm 9|, this switch arm being adapted to cooperate with thecontacts 92 and93. Energization of the relay coil 89 will have theeffect of tending to pull the leg 81 of the armature up wardly therebytending to cause'clockwise rotation of said armature. about its pivot.Similarly, the effect of the relay coil 98 when energized will be totend to cause the leg 88 tobe pulled upwardly, this tending to causecounter-clockwise rotation of said armature. Therefore, when the relaycoils 89 and 98 are equally energized the effect of one upon thearmature will be balanced by the effect of the other and the armaturewill assume an intermediate position in which the switch arm 9| isdisengaged from both the contacts 92 and 93. If, however, the relay coil89 is energized more highly than the relay coil 90 the switch arm 9|will be brought into engagement with the contact 92. Similarly, if therelay coil 90 is more highlyenergized than the relay coil 89 the switcha'rm 9| will be brought into engagment with the contact 93.

Reference character 95 indicates generally a relay comprising switcharms 96, 91 and 98, these switch arms being secured by a suitableconnect-' -ing member to a plunger (not shown), which is located withinthe coil 95a. Cooperating with the switch arms 96, 91 and 98 are incontacts 99, I08 and IOI respectively. Also cooperating with the switcharm 91 is an out contact I02. When the relay coil 95a is energized theplunger will be pulled towards the right thiscausing the switcharms 96,91'and 98 to be moved to the right into engagement with the contacts 99,I80 and MI respectively. When the relay'coil 95a is deenergized,however, the switch arms 96, 91 and 98 will be caused to move towardsthe left under the action of gravity or springs (not shown) this causingsaid switch arms to-disengage from the contacts 99, I and IOI andcausing the switch arm 91 to engage the contact I02.

Located in the conditioned space 6 is a temperature controller I05, thiscontroller comprising a bellows I06 which is filled with a suitablevolatile fluid and which at its lower end is mounted to a suitable fixedsupport. At its upper end said bellows cooperates with the actuating armI81 of a bell crank lever which has as its other arm a control arm I88.The control arm I88 is arranged to cooperate with a control resistanceI09. Attached to the free end of the actuating arm I01 is a spring IIOwhich urges will increase in pressure, this causing expansion of thebellows which acts to rotate the actuating arm upwardly, this causingthe control arm I08 to travel across the control resistance in adirection from left to right. Upon a decrease in temperature thepressure of the volatile fluid within the bellows I06 will decrease,this causing contraction of the bellows under the action of the spring II0 which results in moving of the control arm I08 across the controlresistance from right to left.

Reference character II5 indicates a step-down transformer the primaryII6 of which is connected by wires Ill and H8 to the wires 8 and 9respectively which lead from the line switch I0 to the fan motor 1. Theright-hand end of the secondary II9 of the transformer H5 is connectedto' the lower end of the relay coil 90 by a wire I28 while the left endof said transformer secondary is connected by a wire I2I to the lowerend of the relay coil 89. The upper ends of the relay coils 89 and 90are connected together by a wire I22. In this manner the relay coils 88and 90 are connected in series across the terminals of the transformersecondary II9. Connected to the/lower end of relay coil 89 is aresistance I23, this resistance being connected by a wire I24 to thewire I25 which leads to the upper end of the balancing resistance 83 andby wires I26 and I21 to the left end of the control resistance I09 ofthe temperature controller I05. The lower end of the relay coil 90 isconnected to a resistanceIZS, this resistance being connected to a wireI29 which in turn is connected to a wire I38 which leads to the lowerend of the balancing resistance 83.. The wire I29 is also connected tothe wire I3I which leads to the righthand end of the control resistanceI09. From the foregoing it should be seen that the balancing, resistance83 and the control resistance I08 are connected in parallel with theseries connected relay coils 89 and 90 across the secondary II9 of thetransformer II5. The wire I22 which connects the upper ends of the relaycoils 89 and of the relay coils 89 and 90 are connected to the controlarm I08 of the temperature controller I05 through the switch arm 91 andcontact I00.

With the wiring arrangement just described the portion of the controlresistance I09 between its left-hand end and the control arm I88 isconnectedin parallel with the relay coil 89 by wires I21, I26 and I24,resistance I23 and wires I22, I33, I35, switcharm 91, contact I80, wireI36, and control arm I08. In a similar manner the portion of the controlresistance I09 between the control arm I08 and the right-hand end ofsaid resistance is connected in parallel with the relay coil 98 by wiresI3I, I29, resistance I28, wires I22, I33 and I35, switch arm 91, contactI00, wire I36 and control arm I08. Also by the wiring arrangementdescribed it will be found that the portion of the balancing resistance83 between the control arm 82 and the upper end of said I coil as.

Operation With the parts in the position shown the temperature withinthe space 6 is at an intermediate value as indicated by the control armI 68 of th temperature controller I engaging the center of the controlresistance G06. The relay 95 is also pulled in, this relay being held inbya holding circuit for the relay coil 95a which is as follows:transformer secondary relay coil 95a, wire I411, contact ml, switch arm98, wire I42, and wire I43 to transformer second-e ary H9. The shaft 50of the controller 56 for this position of the controller W5 has assumedan intermediate angular position as indicated by the balancing arm 82 ofthe balancing potentiometer engaging the center of the balancingresistance 86. For this angular position of shaft 5i the switches 66 andM are closed while the switches 62 and 63 remain open. Also the switch59 at this time is open as indicated. The closure of the switch 66causes operation of the pump motor 20 by energizing the pump motorstarter 2i through a circuit as follows: Line wire I45, contact 99,switch arm 96, wire M6, wire 6a, magnetic starter 26, wire t ll, switchBil, wire I46, and wire I49 to line wire l5ll. Closure of switch 6icauses operation of the compressor M by en-.

ergizing the magnetic starter 33 therefor through a circuit as follows:line wire Hid-contact 99), switch arm 96, wire H46, wire l5l, compressormotor starter 36, wire I52, switch 60, wire I53 and wire I49 to linewire 056. For an intermediate value of temperature in the space 5,therefore, the circulating pump l8 and the compressor '27 are placed inoperation by the temperature controller (Hi5.

If now should the temperature within the space 6 increase, the bellowsHit will expand, this causing travel of the control arm: tilt across thecontrol resistance i659 from left to right. This will have the effect ofdecreasing the portion of the control resistance I109 which is inparallel with the relay coil 96 and increasing the portion of saidcontrol resistance which is in parallel with the relay coil 89. Thiswill result in increasing the current flow through the relay coil ,89and decreasing the current flow through the relay coil 90, this causingthe leg til of the relay arma= ture to be pulled upwardly, bringingtheswitch arm 90 into engagement with the contact 92. Engagement ofswitch arm at with contact 92 will energize the field coil it asfollows: trans=-- in parallel with the relay coil 86 and increase theportion of said resistance which is in parallel with the relay coil 9t],this causing progressive decreasing of current flow in relay coil 86 andprogressive increasing, of the current flow in re lay coil 96, thistherefore acting to balance out the initial unbalancing action of thecontroller H9, wire Mil,

I05 on the relay 85 When the angular movement of shaft 5| is such thatthe movement of the balancing arm 62 causes complete re-balancing of therelay 85 the switch arm M will disengage contact 92, this causingstopping of the shaft 5I in this new position. It should therefore beapparent that an increase in temperature within the space 6 will causethe proportioning motor shaft 5I to be rotated in a counterclockfollows:line wire I45, contact 99, switch arm 96,

Wire I46, wire I60, compressor starter 62, wire Iiil, switch 62, wireI52 and wire I49 to line wire I563. Upon further increase in temperaturewithin the space 6 the shaft 5i will be rotated further in a clockwisedirection and when said shaft approaches its extreme counter-clockwiselimit of rotation, the raised portion of the cam 56 will engage thefollower portion 64 of the switch 63 causing closing of this switch.Closing of the switch 63 will cause'operation of the compressor 22 byenergizing the'compressor starter M as follows: line wire Hi5, contact96, switch arm 66, wire 846, wire 666, compressor starter at, wire IGQ,switch 63, wire I65 and wire M9 to line wirei56, It shouldbe apparent,therefore, that as the temperature within the space ii increases thenurn ber of compressors in operation is sequentially increased, thetotal number of compressors be ing placed in operation when thetemperature reaches the upper limit of the operating range of controllerN95,

If the temperature within the space 6 should new fall, the control armHill of the controller E05 will be moved across the control resistanceits from right to left, this decreasing the portion of the controlresistance are which is in parallel with the relay coil 86 andincreasing the portion of said resistance which is in parallel with therelay coil 9t. This will cause a greater current flow to occurin relaycoil 9d than occurs in the relay-coil 86, which results in the switcharm 9i engaging the contact 93. Engagement of the 4 switch arm 9i withcontact 93 will energize field coil 15 by a circuit as follows:transformer secondary M9, wire lit, switch arm 99, contact 96, wire 866,limit switch 86, wire 86?, field coil l5, wire I56 and wire Hi totransformer secondary H6. Energization of field coil '65 will causerotation of the shaft 5i in a clockwise direction and i will cause thebalancing arm 82 of the balancing potentiometer to move downwardlyacross the balancing resistance 83, this decreasing the portion of saidresistance which is in parallel with relay coil 6% and increasing theportion of said resistance which is in parallel with relay coil 86. Thiswill decrease the current flow in relay coil 99 and increase the currentflow in relay coil 89 thereby tendingto balance out the initialunbalancing effect of the controller 185 upon the relay 85. When thecounterclockwise movement of shaft 5i is suflicient to cause thebalancing potentiometer to completely balance out the unbalancing effectof the controller M35, the switch arm M will disengage from contact 96,this causing stopping of the shaft M in its new position.

The shaft 5I is therefore rotated in a clockwise direction upon fallingtemperature within the space 6. As the temperature within the space 0falls the resulting clockwise rotation of shaft 5I will first causeopening of the switch 03, this placing the compressor, 22 out ofoperation. Upon further fall in temperature the switch 62 will be open,this placing the compressor23 out-of operation and upon saill furtherfall in temperature the switch 8| will be opened this placing compressor24 out of operation. Upon a further fall in temperature the switch 60will be opened, this resulting in the pump I8 being stopped. This willoccur when the temperature within the space 6 falls to the lower limitof the operating range of the controller I05.

From the foregoing it should be apparent that so long as the relay 95remains energized the controller I05 will be in control of thecirculating pump and the compressors, such controller acting upon anincrease in temperature to first place the circulating pump in operationand upon further increase in temperature to sequentially place thecompressors in operation. It should also be apparent that under fallingtemperature the reverse action will take place, that is, the compressorswill be sequentially placed out of operation and finally the circulatingpump will be stopped.

If a power failure should occur the relay coil 95a will be deenergizeddue to lack of energizing current, this causing the switch arms 96, 91and 98 to disengage the contacts 99, I00 and IOI and further causing theswitch arm 91 to engage the contact I 02. Disen'gagement of the switcharm 96 from contact 99 will break the energizing circuit for the motorstarters 2|, 3|, 32 and. 33. Therefore, the circulating pump andcompressors will be prevented from operating when resumption of powereven though the temperature within the space may be such that theswitches 60 to 63 are all closed. Disengagement of the switch .arm 98from contact lIlI will break the holding circuit for the relay coil 96previously described and therefore if the power should come on, therelay coil 95a will not be immediately energized. Engagement of theswitch arm 91 with the contact IOI will cause a shunt circuit to becompleted around the relay coil 89, this circuit being as follows: relaycoil 89, wire I22, wire I33,

wire I35, switch arm 91, contact I02, wire I21, wire .I26, wire I24 andresistance I23 to the other side of relay coil 89.

Upon resumption of power, the relay coil 90 will become energized whilethe relay coil 89 willbe substantially short-circuited as abovedescribed. Due to this unbalancing the switch arm 9I will engage thecontact 98, this causing energization of the motor field 15 to rotatethe shaft 5I in a counter-clockwise direction. Due to the completeshunting of the relay coil 89 the balancing potentiometer will beincapable of rebalancing the relay and therefore the switch arm 9| willremain engaged with the contact 93 and the shaft 5I will be driven toits extreme limit of clockwise rotation, at which time the raisedportion 51 of the cam 52 will engage the switch 59 causing closing ofthis switch. Also at this time the cam 16 will engage the limit switchcausing opening of this switch and deenergizlng of the field coil 15.With the shaft 5I in its extreme limit of clockwise rotation therecessed portions of the cams53 to 56 will engage the switches 60 to 63and hence all of these switches will be open. It should be seen,therefore, that engagement of the switch arm 91 with -relay coil 95a,wire HI,

the contact I02 will upon resumption of power cause the proportioningmotor shaft 5| to be rotated in its extreme clockwise limit of rotationat which position the pilot switches for the motor starters are allopened and the switch 59 is closed.

- The closure of the switch 59 will cause energization of the relay coil95a by a circuit as follows: transformer secondary II9, wire I40, wireI98, switch 59, wire I89 and wire I43 to transformer secondary II9.Energization of the relay coil 95a will cause the switch arms 98, 91 and98 to be brought into engagement with the contacts 99, I00 and IOI.

Engagement of the switch arm 98 with contact 'IOI will re-establish theholding circuit for the relay'coil 95a which is as follows: transformersecondary II9, wire I43, wire I42, switch arm 98, contact IOI, wire I4I,relay coil 95a. and wire I40 to transformer secondary H9. The relay coil95a will therefore remain energized even though the switch 59 may laterbe opened. Engagement of switch arm 96 with the contact 99 will have no;immediate result due to the fact that the switches 60, GI, 62 and 63 areall opened. However, due to engagement of switch arm 96 with contact 99the switches 60 to 63 will be conditioned to cause starting of theirrespective motors when they are caused to close by counter-clockwiserotation of shaft 5I. Due to the switch arm 91 disengaging the contactI02 the shunt circuit for the relay coil 89 will be broken and due tothe switch arm 91 engaging the contact I00 the controller I08 will bereplaced in control of the relay 85. As the balancing arm 82 of thebalancing potentiometer will be engaging the extreme lower end of thebalancing resistance 83 the relay coil 90 will be substantially shuntedout while the entire balancing resistance 83 will be in parallel withthe relay coil '89. The relay coil 89 will therefore be more highlyenergized than the relay coil 90, this causing engagement of the switcharm 9I with the contact 92 which results in energizing the field coil14, this in turn causing rotation of the shaft M in a counter-clockwisedirection, this counterclockwise rotation causing sequential actuationof the switches 60 to 63, the number of switches actuated depending uponthe degree of counterclockwise rotation. When the counter-clockwisemovement of the shaft 5| becomes such that the balancing potentiometercauses rebalancing of the relay the switch arm 9I will disengage fromcontact 92, this stopping the shaft 5I in this position, As the requiredmovement of the balancing potentiometer for balancing the relay 85 isdependent upon the position of the control arm I08 on the resistanceI09, the movement of shaft 5| will be dependent upon the temperaturewithin the space 6.

From the foregoing, it should be apparent that upon a failure of power,the control of the sequential controller 50 by the temperaturecontroller I05 will be temporarily discontinued and the sequentialcontroller 50 will be caused to rotate'to a position in which all of themotors are disconnected from their source of power, at which time thesequential controller 50 is again placed under the control of thetemperature controller I05, this causing it to reassume an angularposition corresponding to the temperature in the space 6? In reassumingthe angular position called for by the controller I05 the appropriatenumber of switches 60 to 63 are operated sequentially and hence thevarious motors are sequentially replaced in operation.

Due to this sequential restarting of the motors heavy surges in current,such as would occur if all the motors werestarted simultaneously, areavoided.

It should be noted that due to the transformer 5 being connected to theload side of the line switch ill the relay coil 96 will be deenergizedwhenever the line switch it is opened, this resulting in shutting downof the motors in operation due to disengagement of the switch arm 9tfrom contact 99, and results also in causing the controller to be run toan off position before any of the motors can be restarted, thecontroller 50 acting also to sequentially restart the motors When'thetransformer M5 is again energized. Thus by opening the switch 88 thesystem may be placed out of operation and by merely closing the switchit the fan i will be placed into operation and the controller 5@ willcause starting of the, pump motor 2d and the number of compressor motorsas called for by the controller i615.

In the illustrated embodiment of my invention, it will be observed thatboth the step-controller motor and the relay 95 receive their energizingcurrent from a single transformer, this transformer being connected tothe fan circuit. If desired, the step-controller motor may be energizedby a separate source of power than that which supplies the fan motor andthe other motors, thus permitting the step-controller to move to offposition immediately after an interruption of power to the fan motor,instead of remaining in its original position until restoration ofpower, as occurs in the illustrated embodiment. With the arrangementjust described, the switch arm as and contact ill] of the relay Slicouldbe eliminated.

While I have illustrated my invention as applied to a spray type of airconditioning system, it will be apparent that it is also applicable todirect expansion types of systems. The water pump may in such case beused for pumping condensing water, or if desired, it may be omitted.Furthermore, while I have illustrated the reirigeration system ascomprising a plurality of compressors, it is to be understood that ifdesired, a single multi-speed compressor may be employed, the speed ofsuch compressor being varied by the step-controller or equivalentarrangement. Also, it is to be understood that my invention isnotlimited to an air conditioning or refrigerating apparatus, butisapplicable in its broader principles to control of other types of powerconsuming devices or control devices. It will be apparent that manychanges whichare'within the scope of my invention will suggestthemselves to those skilled in the art. I therefore desire to be limitedonly by the scope of the appended claims and the prior art.

I claim as my invention:

1., Inan air conditioning system, in combination, an air conditioningchamber through which air is passed, means connecting said conditioningchamber with a space to be conditioned, cooling means in saidconditioning chamber for cooling the air as it is passed through thechamber, means for supplying a cooling fluid to said cooling meansincluding a power driven pump,

means for chilling the cooling fluid comprising a compressionrefrigeration system including a plurality of independently drivencompressors, a source of power for said pump and said compressors,sequential control means for se quentially placing said pump and saidcompressors in operation, condition responsive means for controllingsaid sequential control means, means responsive to a failure of powerfor placing said condition responsive means out of operation and forcausing said sequential control means to be operated to disconnect saidsource of power from said pump and said compressors, and means actuatedwhen said sequential controller discon nects said pump and saidcompressors for replacing said condition responsive means in control ofsaid sequential control means.

2. In an air conditioning system, in combina tion, an air conditioningchamber through which air is passed, means connecting said conditioningchamber with a space to be conditioned, cooling means in saidconditioning chamber for cooling the air as it passes through thechamber, means for supplying a cooling fluid to said cooling means,means for causing chilling of the cooling fluid comprising a pluralityof independently driven compressors, a source of power therefor,sequential control means for sequentially placing said compressors inoperation, condition responsive means for controlling said sequentialcontrol means, means responsive to a failure of power for placing saidcondition responsive means out of operation and for causing saidsequential control means to be operated to a position in which saidsource of power is disconnected from said compressors, and meansactuated when said sequential controller reaches the position mentionedfor replacing said condition responsive means in control of saidsequential control means.

3. In a system of the class described, in combibination, a plurality ofpower consuming devices, control means'for sequentially placing saidpower consuming devices in operation, and means operable upon a failureof power for causing a se quential replacing of said power consumingdevices in operation upon resumption of power.

a. In a system of the class described, in combi= nation, a plurality ofpower consuming devices, a plurality of control devices therefor, motormeans for sequentially actuating said control devices, load responsivemeans for controlling said motor .means, and means responsive to thepower supply for temporarily dominating the control 0:? said loadresponsive means over said motor means upon the occurrence of apredetermined condition in said power supply.

5. In a system of the class described, in combination, a plurality ofpower consuming devices, a plurality of control devices therefor, motormeans for sequentially actuating said control devices, load responsivemeans for controlling said motor means in a manner to cause the powerconsuming devices to be sequentially placed in oper ation upon increasein load, and means operable upon a failure of power for causing saidmotor means to sequentially replace said power consuming devices inoperation.

6. In a system of the class described, in combination, a plurality ofpower consuming devices, a plurality of control devices therefor, motormeans for sequentially actuating said control devices, load responsivemeans for controlling said motor means in a manner to cause the powerconsuming devices to be sequentially placed in operation upon increasein load, and means operable upon a failure of power for operating saidmotor means independently of. said load responsive means-to a positionin which the power @WlSl/illiil'lg devices are out of operation, and fortiienre storing the control of said motor means to said load responsivemeans.

'7. n1 a system of the class described, a plurality of control devices,motor means for sequentially actuating said control devices, conditionresponsive means controlling said motor means for causing sequentialactuation of said control devices ina predetermined program inaccordance with the condition to which it is responsive, and meansresponsive to the medium controlled by said control devices alsocontrolling said motor means.

8. In a system of the class described, a plurality of control devices,step control means for sequentially actuating said control devices,condition responsive means for controlling said step control means, andmeans responsive to the medium controlled by said control devices forcausing recycling of said step control means upon the occurrence of apredetermined condition of such medium.

9. In a system of the class described, in combination, a plurality ofcontrol devices, means for sequentially actuating said control devices,motor means for positioning said actuating means, control means for saidmotor means, and means operable upon the occurrence of a predeterminedcondition for operating said motor means independently oi the controlmeans to move said actuating means to a predetermined position, and forthen restoring the control of said motor means to said control means.

10. In a system of the class described, in combination, a controller,motor means for actuating said controller, control means for said motormeans, and means operable upon the occurrence of a predeterminedcondition for operating said motor means independently of said controlmeans to a predetermined position and for then restoring the control ofsaid motor means to said control means.

11. In a system of the class described, in combination, power consumingmeans, a controller for said power consuming means, motor means foractuating said controller, load responsive means for controlling saidmotor means, and means operable upon a failure of power for causingoperation of said motor means independently of said load responsivemeans in a direction to position said controller for preventing supplyof power to said consuming means, and means for then restoring thecontrol of said motor means to said load responsive means.

12. In a system ofthe class described, in combination, power consumingmeans, control means for progressively controlling said power consumingmeans, and means operable upon a failure and subsequent resumption ofpower for progressively replacing said power consuming means inoperation.

13. In a system of the class described, in com bination, a progressivecontrol device, motor means for actuating said progressive controldevice, control means for said motor means, means for placing saidcontrol means out of operation and for causing said motor means to movesaid progressive control device towards a predetermined position, andcontrol means automatically actuated upon the progressive control devicereaching the predetermined position, for replacing said control means incontrol of said motor means.

14'. In a system of the class described, in combination, a plurality ofcontrol devices, movable means for sequentially actuating said controldevices, motor means for driving said movable means, control means forcontrolling said motor means, means for placing said control means outof operation and for causing said motor means to drive said movablemeans towards a predetermined position, and means automatically actuatedupon the movable means reaching said predetermined position forreplacing said control means in control of said motor means.

15. In a system of the class described, in combination, a progressivecontrol device, motor means for actuating said progressive controldevice, control means for said motor means, means responsive to thecondition of the medium controlled by saidprogressive control device forplacing said control means out oi operation upon said condition varyingto a predetermined value, said condition responsive means also causingsaid motor means to move said progressive control device towards apredetermined position, and control means automatically actuated uponthe progressive control device reaching the predetermined position, forreplacing said control means in control of said motor means.

16. In a system of the class described, in combination, a plurality ofcontrol devices, movable means for sequentially actuating said controldevices, motor means for driving said movable means, control means forcontrolling said motor means, means responsive to the condition of themedium controlled by at least one of said control devices for placingsaid control means out of operation upon such condition varying to apredetermined value, said condition responsive means also causing saidmotor means to drive said movable means toward a predetermined position,and means automatically actuated upon the movable means reaching saidpredetermined position for replacing said control means in control ofsaid motor means.

17. In a system of the class described, in combination, a powerconsuming means, progressive control means for said power consumingmeans, motor means for actuating said progressive control means, loadresponsive means for controlling said motor means to position saidprogressive control means in accordance with load conditions, and meansoperable upon failure of power for placing said load responsive meansout of operation and for operating said motor means to run saidprogressive means towards "ofP position, and means actuated upon saidprogressive control means reaching a predetermined position forreplacing said load responsive means in control of said motor means. 7

18. In a system of the class described. in combination, a plurality ofpower consuming devices. sequential control means for sequentiallyplacing said power consuming devices in operation, motor means foractuating said sequential control means, load responsive means forcontrolling said motor means to cause actuation of said sequentialcontrol means upon change inload, meansoperable upon failure of powerfor placing said load responsive means out of operation and forenergizing said motor means to drive said sequential control meanstowards "ofl position, and means actuated upon said sequential controlmeans reaching a predetermined position for replacing said loadresponsive means in control of said motor means.

FRANCIS B. FJILO.

DISCLAIMER 2,157 ,329.Francis B. Fillo, Webster Groves, M0. CONTROLSYSTEM. Patent dated May 9, 1939. Disclaimer filed April 26, 1940, bythe assignee, Minneapolz's-Honeywell Regulator Company.

Hereby disclaims the subject matter of each of claims 3, 4, 5, 6, 7, 8,9, 10, 11,

12, 13, 14, 15, 16, 17, and 18 of said Letters Patent.

[Ojficz'al Gazette May 21, 1940.]

DISCLAIMER 2,157,329.-Francis B. Fillo, Webster Groves, M0. CONTROLSYSTEM. Patent dated May 9, 1939. Disclaimer filed April 26, 1940, bythe assignee, Minneapol'is-Honeywell Regulator Company. Hereby disclaimsthe subject matter of each of claims 3, 4, 5, 6, 7, 8, 9, 10, 11, 12,13, 14, 15, 16, 17, and 18 of said Letters Patent.

[Ofiicial Gazette May 21, 1940.]

